Interpretive Summary: Each year, commercial poultry meat production in Mississippi generates 455,000 tons of poultry litter (a mix of bird feces and decomposed saw dust) which is commonly used as a fertilizer for nearby pasture and croplands. With many years of application of litter to fields, the concentration of nutrients in the soil increases and the possibility increases for those nutrients to be washed from the fields during rains and pollute streams. Critical to managing the risk of water pollution from poultry litter fertilization is the time between when the litter is applied to the land and the next rain. This research showed that as the time to the first rain increased from 0 to 9 days the pollution in the water decreased. With a modest artificial rain of 1/3 of an inch. the water running from the plots 9 days after litter fertilization had 64% less nitrogen and 43% less phosphorus than water with rains on day zero. This research shows that it is unadvisable to fertilize any fields with poultry litter when rain is likely in the near future. With a simple directive to the farmers of do not apply manure to the fields during rainy days or when rain is likely, the amount of water pollution is greatly reduced.

Technical Abstract:
Concern over water quality degradation has directed attention to animal manure management effects on nutrient losses in runoff. This study evaluates the effects of time of broiler litter application relative to occurrence of rain events on nutrient concentrations in runoff from a Ruston sandy loam (Fine, mixed active, thermic Aquic Hapludults) soil established with bermudagrass (Cynodon dactylon L.). Air-dried soil was packed into runoff boxes (144 cm long, 20 cm wide, and 10 cm deep) at bulk density of 1.30 g cm-3. Bermudagrass was established by plugging (26 plugs per box). Broiler litter was broadcast at the rate of 9 Mg ha-1. Simulated rainfall (27 mm h-1) was applied until 15 min of runoff was collected at 0, 3, 6, and 9 d after broiler litter application. Also, 8 successive rainfall events were applied at 3 d intervals to the soil incubated for 9 d with broiler litter and commercial fertilizer to evaluate how rainfall frequency affects nutrient dynamics in runoff to obtain technical support for broiler litter management. As the length of time between broiler litter application and rainfall events increased from 0 to 9 day runoff total N, NH4-N, and NO3-N decreased by 50%, 64%, and 31%, respectively. Total P and dissolved P concentrations in runoff decreased to 35% and 43% of initial time of application values (0 d), respectively. Runoff N, P, K, Ca, Mg, Cu, and Zn concentrations decreased with successive rain events and approached the ones in unfertilized soil. Avoiding litter applications during periods of possible high intensity rainfall reduces the potential environmental hazard.